Very much so.
There are cycles and mini cycles. Throughout a normal day I will get small ups and down, and there are bigger and more extreme waves that take place over months. I would go months content with my own occasional fantasies, to suddenly feeling compelled to seek out every single TG type of material I can possibly find.
In fact, this time last year I was suffering perhaps the single worst wave of my life. It was the one that finally broke me out of being a "dark crossdreamer," It had it's own smaller ups and downs but overall lasted April till about Jan-Feb. I think it was particularly long lasting because I was in denial about that part of myself for so long.
I have been on a low since then, but feel like I am on the start of another upswing again. I guess this is what is meant by the term "Gender fluid."
As for why this happens, I don't know but I think that our crossdreaming side is fighting against our own coping mechanisms and the latter are getting worn down and having to rest.
I think this because I have noticed that my own crossdreaming episodes seem to, on average, last longer and longer and increase in intensity. Something you would expect if your coping mechanisms are wearing down.
Edit: I wanted to add one thing. Lately I have noticed that the waves ALWAYS intensify as I try to go to sleep.